Electrical time delay apparatus



Sept. 18, 1951 T. MILL ER 2,568,403

ELECTRICAL TIME DELAY APPARATUS Filed Oct. 17, 1949 WITNESSES: INVENTOR Theodore Miller. M

WW W ATTOFANEY Patented Sept. 18, 1951 ELECTRICAL TIME DELAY APPARATUS Theadore Miller, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 17, 1949, Serial No. 121,876

Claims.

My invention relates to electric discharge apparatus, and more particularly to delay lines.

In accordance with the prior art of which I am aware, devices have been built for timing the flow of electrical energy wherein an electron beam generated at one end of a vacuum tube has been caused to spiral inside the vacuum tube in response to a magnetic field applied by an external magnet. This device has the disadvantage that the electron beam has an inherent defocusing tendency which is extremely undesirable. Since the effect of defocusing on the signal increases greatly as the frequency increases, the frequency range for which these devices were op erable was extremely limited.

Those devices also have the disadvantage of requiring a large and cumbersome magnet surrounding the vacuum tube in order to produce the magnetic field which controls the electrons.

It is, accordingly, an object of my invention to provide apparatus for the time delay of an electrical signal with a wide frequency range.

Another object of my invention is to provide apparatus for the time delay of electrical energy which will not incorporate an external magnet.

Still another object of my invention is to provide a new and novel electronic discharge device. In accordance with my invention, I provide a vacuum tube having an electrical conductor extending through the tube in substantially a straight line. An electric current is caused to pass through this wire, thereby producing a magnetic field having fiuxlines which are circular and extend about the wire, as is well known in the art. A source of electrons such as an electron gun is provided at one end of the vacuum tube, and an anode is provided at the other end. Electrons leaving the electron gun are caused by that gun to travel initially in a direction lying in a plane perpendicular to the electrical conductor extending through the tube. These electrons will be caused by the magnetic field about the wire to spiral about a flux line while circling around the electrical conductor. The forces which cause these electrons to spiral about a flux line are relatively strong and therefore a high degree of control is maintained over the electrons. An electrode which substantially fills the end of the tube is placed between the anode and that end of the tube nearest the anode. This electrode has a potential impressed thereon which is positive with respect to the cathode of the electron gun. A field i thus established through the tube which will cause the electrons spiraling about the flux lines to slip downward toward the anode. The time required for electrons leaving the electron gun to reach the anode may be controlled by adjustment of the potential on the acceleratin electrode.

The novel features which I consider characteristic of my invention are set forth with more particularity in the appended claims. The invention, however, with respect to both the organization and the operation thereof, together with other objects and advantages may be best understood from the following description of specific embodiments with reference to the accompanying drawing in which the single figure is a schematic showing of apparatus embodying my invention.

In accordance with my invention, I provide a vacuum tube 3 having a wire 5 of electrical conducting material, such as copper. extending therethrough. At each end of the tube 3 encircling the wire conductor 5 are large plates I. 9 of conducting material. These two plates are the acceleration electrodes, a potential being applied between them so as to produce an electric field within the tube. Near the negative acceleration electrode 1 is an electron gun. This electron gun may be of any of several designs which are well known in the art, the one shown in the drawing being only an example. Preferably the gun should have a cathode 8, a grid II and a primary accelerating electrode [3. Connections are supplied between the cathode 8 and the grid H for impressing a signal potential between those two. The signal potential applied between the cathode and the grid controls the intensity of the electron beam supplied by the gun. A source of potential I2 is connected across the central electrical conductor 5 to produce a substantial current therein, and produce as a result of that current a magnetic field about that conductor. At the other end of the vacuum tube from that at which the electron gun is located is an anode IS. The anode I5 is placed at such a distance from the central electrical conductor 5 that it will intercept the path of electrons spiraling about the central conductor. The action of the magnetic field about the central conductor on the electrons will be discussed in detail later. The cathode B of the electron gun is connected to ground and the anode l5 of the vacuum tube is connected through an output resistance l1 and a battery 19 to ground. The primary accelerating electrode ii! of the electron gun is connected through a resistance to a point 2| on the last-mentioned battery such that the potential of the primary accelerating electrode l3 of the electron gun will be at a potential more negative than the tube anode I and more positive than ground. Connections 23 are supplied on either side of the output resistance II for impressing the potential de veloped across the output resistance II on such apparatus as one wishes to have responsive to that signal. The primary accelerating electrode I3 of the electron gun may be connected through a resistance 25 to the central electrical conductor 5 so as to maintain the potential of the central electrical conductor 5 substantially equal to the potential of the primary accelerating electrode I3 of the electron gun as may be desired under some operating conditions. In order to vary the magnetic field about the central conductor 5, I have provided a variable resistance 21 connected in series between the source of potential I2 and the central conductor 5 in the embodiment of my invention shown in the drawing. Changing the variable resistance 21 will cause a variation in the change the radius of their path. It was men- ,1

tioned above that a potential is connected between the positive accelerating electrode 9 and ground. A pair of terminals 29 may be placed in series between this source of potential and the positive accelerating electrode 9 across which a signal potential may be applied. A signal potential applied across these terminals would change the potential of the accelerating electrode '9 and, therefore, change the time required for the electrons to travel from the electron gun to the anode I5. I would, therefore, have a method of delay modulation in addition to the amplitude modulation eifected by the control grid II of the electron gun.

In the operation of the embodiment of my invention shown in the drawing, electrons from the cathode 8 of the electron gun are attracted toward the primary accelerating electrode l3 when the grid II is of such a potential as to allow their passage. As the primary accelerating electrode I3 is a hollow cylinder with its long dimension parallel to the path of the electrons, most of the electrons will pass through the primary accelerating electrode I3 and into the open space beyond. A force will now be directed against the moving electrons 3| by the magnetic field about the central electrical conductor 5. This force will tend to force the electrons 3| to spiral about one of the flux lines of the magnetic field established by the current in the central conductor. If there were no electrical field across the tube these elec trons would continue to spiral about a flux line substantially travelling the same path each time they encircle the central electrical conductor. However, with the electrical fields supplied by the accelerating electrode at each end of the tube, the electrons will be caused to gradually spiral downward toward the anode I5. If the electrical and magnetic fields are properly adjusted the electron will eventually strike the anode I5. The anode is thus positioned at a distance from the central conductor 5 equal to the mean radius of the path of the electrons as they encircle the central conductor.

It is to be noted that I have a double spiraling action. There is the spiraling of the electrons about the flux lines which I shall call the small spiral, and there is the spiraling of the electrons as they changefrom one flux line to the next while moving around the central conductor and downward toward the positive accelerating electrode. This last spiraling action I shall call the large spiral. The anode is, therefore, at a distance from the central conductor equal to the radius of the large spiral.

For some purposes it will be desirable to pass two signals'through the same tube at the same time. This may be done by supplying a second electron gun comprising a second cathode 33, grid 35, accelerating anode 31, and a second anode 99. The potential of the accelerating anode 31 of the second gun is chosen at a different quantity from the potential of the primary accelerating electrode I3 of the first electron gun. The radius of the large spiral of the electrons 3| produced by the first gun will then be difierent from the radius of the large spiral of the electron 4| produced by the second gun. The second anode 39 is located in such a position that it will intercept electrons I produced by the second electron gun and will not intercept electrons 3| produced by the first electron gun. The two signals may thus pass through the tube simultaneously without interference with each other.

The potential of the positive accelerating elec- .trode 9 should, for most purposes, be made less positive than the potential of the anodes I5, 39. If the positive accelerating electrode 9 is too positive, the electrons will be accelerated too rapidly to produce the time delay desired for most purposes.

Although I have shown and described specific embodiments of my invention, I am aware that other modifications thereof are possible. My invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and the spirit of the invention.

I claim as my invention:

1, In combination, a vacuum tube, an electrical conductor extending through said vacuum tube, a source of electrons near one end of said vacuum tube, an anode near the other end of said vacuum tube, an accelerating electrode located between the anode and that end of the tube nearest the anode, connections for applying a potential across said electrical conductor.

2. In combination, a vacuum tube, an electrical conductor extending through said vacuum tube, a source of electrons near one end of said vacuum tube, an anode near the other end of said vacuum tube, an accelerating electrode located between the anode and that end of the tube nearest the anode, connections for applying a potential across said electrical conductor, an electrode between said source of electrons and that end of said vacuum tube which is nearest said source of electrons.

3. In combination, a vacuum tube, an electrical conductor extending through said vacuum tube, a source of electrons near one end of said vacuum tube, an anode near the other end of said vacuum tube, and accelerating electrode located between the anode and that end of the tube nearest the anode, connections for applying a potential across said electrical conductor. an electrode between said source of electrons and that end of said vacuum tube which is nearest said source of electrons, connections for applying a potential to said acccelerating plate in response to a signal.

4. In combination, a vacuum tube, an electrical conductor extending through said vacuum tube, a source of electrons near one end of said vacuum tube, an anode near the other end of said vacuum tube, an accelerating electrode located between the anode and that end of the tube nearest the anode, connections for applying a potential across said electrical conductor, an electrode between said source of electrons and that end of said vacuum tube which is nearest said source of electrons, connections for applying a signal potential to said source of electrons in such manner as to cause the number of electrons produced per unit time to be responsive to the amplitude of said signal current.

5. Apparatus for the time delay of electrical energy, comprising a vacuum tube having therein a plurality of anodes near one end of said tube and a plurality of sources of electrons, each of said sources of electrons being a substantial distance from at least one of said anodes. a wire extending through said tube from the region of one of said sources of electrons to the region of one of said anodes, and connections supplying a current to said wire.

THEADORE MILLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

